Voltaic Construct + Mycosynth Lattice + Gumato

Voltaic Construct

Mycosynth Lattice

Gumato

How it works

1. Activate Gumato by tapping it, adding
2. Activate Voltaic Construct by paying 2, untapping Gumato.
3. Repeat

By blanketing the entire battlefield in steel with Mycosynth Lattice, every permanent becomes an artifact in addition to its other types—crucially transforming Gumato into an artifact creature. This allows Voltaic Construct to target and untap Gumato for a mere two mana. Because Gumato taps to generate three green mana, you generate a net surplus of one mana on every single iteration of the loop, fueling infinite green mana and unlimited untaps for your entire mechanical army.